Optimal VAr expansion considering ATC using Strength Pareto Evolutionary Algorithm

This paper presents the application of Strength Pareto Evolutionary Algorithm (SPEA) to find the optimal solution of VAr expansion problem considering the enhancement of Available Transmission Capacity (ATC). The problem is formulated as a nonlinear constrained multi-objective optimization problem. The aim is to obtain an optimal allocation of VAr devices that is optimal in terms of minimizing the total incurred cost and maximizing the amount of ATC. To procure the exact cost of the VAr expansion problem, operation and control costs during all system transition states are calculated. Corrective/preventive controls are utilized to maintain the desired voltage security level. Installation of new VAr devices is proved to improve the amount of ATC, on the other hand it increases the investment cost which conflicts with the objective function of VAr expansion problem. Therefore, an evolutionary technique called SPEA is used to optimize the objective functions simultaneously. The proposed approach has been successfully tested on IEEE 14 bus system.